ML20138E404

Summary of 970313 Meeting W/Westinghouse in Rockville,Md Re Overall Conclusions from AP600 Notrump Computer Code Final V&V & Addl Documentation Which Will Be Included in Revised Final V&V Rept

ML20138E404
Person / Time
Site:	05200003
Issue date:	04/29/1997
From:	Huffman W NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9705020186
Download: ML20138E404 (41)

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4 UNITED STATES NUCLEAR REGul.ATORY COMMISSION of WASHINGTON. D.C. 205:5-0001

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April 29,1997 APPLICANT: Westinghouse Electric Corporation PROJECT:

AP600

SUMMARY

OF MEETING TO DISCUSS AP600 NOTRUMP SMALL BREAK LOSS-0F-l COOLANT CODE VERIFICATION AND VALIDATION (V&V)

The subject meeting was held on March 13, 1997, in the Rockville, Maryland, offices of Westinghouse Electric Corporation between representatives of I

Westinghouse and, the Nuclear Regulatory Commission staff.

The purpose of the meeting was to discuss overall conclusions from the AP600 NOTRUMP computer code final V&V, additional documentation which will be included in the revised final V&V report, and information to be presented to the Advisory Committee

-for Reactor Safeguards (ACRS).

Highlights from the meeting include the following items:

i Westinghouse noted that based on a quality assurance check of calc notes, some corrections would be made to the NOTRUMP final-V&V.

The SPES 2-inch cold leg balance line break (S01007) simulation did not i

accurately reflect the test break location and will be revised in the final V&V report.

Westinghouse presented calculations that showed no i

I significant changes in the simulation results with the corrected break location. The final V&V will be corrected.

Westinghouse stated that for the SPES test comparisons, the PRHR loop is removed after ADS-3 to enhance the running time.

Westinghouse also stated that NOTRUMP tends to underpredict PRHR heat transfer but that this only impacts small break simulations (less than 2-inch equivalent diameter breaks).

NOTRUMP tends to predict delayed ADS actuations relative to the tests at both SPES and OSU.

The noding and models used for OSU, SPES, and AP600 calculations are consistent and differences are due to facility and plant differences.

In general, for the OSU simulations, NOTRUMP underpredicts ADS flows and overpredicts break flows to the extent that total mass inventory tends to be consistently underpredicted.

4 NOTRUMP simulations of small breaks (lest than 2 inches) are not predicted as well as larger breaks because of the underprediction of 3

PRHR heat transfer and lack of a thermal stratification model for the

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CMT.

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l April 29, 1997 Westinghouse also discussed some documentation issues in the final V&V and how they would be addressed.

The changes Westinghouse intends to make are sumoarized below:

the SPES mixture level plots will be revised to account for variable l

area fluid modeling.

l The comparison of AP600 NOTRUMP calculation with volumetric flow-based momentum equations versus mass flow-based momentum equations will be removed from the final V&V (Section 3.5).

Westinghouse stated that the final version of the NOTRUMP code cannot be switched between volumetric and mass flow-based versions and that all calculations are now done with volumetric flow-based momentum equations.

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Westinghouse developed a quench model for NOTRUMP for cases where core nodes uncover and then recover with a large, instantaneous increase in mixture level.

Westinghouse has concluded that the quench model is not l

needed for AP600 NOTRUMP calculation and h:s not included a description l

in the final V&V report.

However, Westinghouse noted that some of the G-2 benchmarking problems required the use of the quench model due to output spiking and run failures. Westinghouse still plans to include those G-2 plots where the quench model was used.

The staff recommended that plots of the G-2 cases with and without the quench model be included in the final V&V and that Westinghouse clearly state that the quench model will not be used for design basis analysis of the AP600.

The staff had stated in the SDSER that the NOTRUMP levelizing model was only used in some limited cases. Westinghouse noted that the final i

version of NOTRUMP will use the levelizing model for all horizontal flow links.

Preparation for an upcoming presentation to the ACRS on the NOTRUMP computer l

code was also discussed. Westinghouse is preparing a summary background l

report on NOTRUMP which it will issue for the ACRS prior to the meeting.

The meeting was productive and progress towards resolution of the remaining issues was made.

Westinghouse agreed to the following actions (which would be documented in the Open Item Tracking System) as a result of discussion during the meeting:

Copies of the NOTRUMP related request for additional information (RAI) l responses and the background summary report being prepared for the ACRS l

will be included in the updated NOTRUMP final V&V report.

Responses to RAIs 440.215 and 440.216 will be incorporated into the text of the final V&V.

Similar to the documentation for the NOTRUMP final V&V, Westinghouse will include a background summary and all appropriate RAI responses in the LOFTRAN CAD.

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i April 29, 1997 is the list of meeting attendees. Attachment 2 is a copy of the presentation handouts with material removed which Westinghouse claims is proprietary. Westinghouse committed to submit via separate correspondence an application for withholding, affidavit, and non-proprietary copy of the proprietary presentation material.

A draft of this meeting summary was provided to Westinghouse to allow them the opportunity to ensure that the representation of comments and discussion was accurate.

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original signed by:

William C. Huffman, Project Manager l

Standardization Project Directorate Division of Reactor Program Management l

Office Of Nuclear Reactor Regulation Docket No.52-003 Attachments: As stated cc w/atts: See next page DISTRIBUTION w/ attachment:

Docket File PDST R/F TKenyon PUBLIC WHuffman DJackson l

JSebrosky DISTRIBUTION: w/o attachment:

Scollins/FMiraglia, 0-12 G18 RZimmerman, 0-12 G18 AThadani, 0-12 G18 TMartin MSlosson TQuay JMoore, 0-15 B18 WDean, 0-17 G21 ACRS (11)

GHolahan, 0-8 E2 FEltawila, T-10 G6 Alevin, 0-8 E23 i

RLandry, 0-8 E23 F0dar, T-10 E46 JLyons, 0-8 E23 l

4 DOCUMENT NAME: A:~i 13-NTP. SUM (6F AP600 DISK) n

.h,...,. w. *.u nt, m.t. w in. w,x: c. cony==nout.it. chm.nt/.new.or.

r - copy with.et. chm.nt/.ncio.or.

n - No cony OFFICE PM:PDST:DRPM SC:DSSMSSXB, D:PDST:DRPM NAME WCHuffman:s1 f-.LAlevin fr// \\

TRQuay -TM DATE 04/% /97 04/7///W/

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04/ 11/97 0FFICIAL RECORD COPY l

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i Westinghouse Electric Corporation Docket No.52-003 cc:

Mr. Nicholas J. Liparulo, Manager Mr. Frank A. Ross Nuclear Safety and Regulatory Analysis U.S. Department of Energy, NE-42 Nuclear and Advanced Technology Division Office of LWR Safety and Technology Westinghouse Electric Corporation 19901 Germantown Road P.O. Box 355 Germantown, MD 20874 Pittsburgh, PA 15230 l

Mr. Ronald Simard, Director l

Mr. B. A. McIntyre Advanced Reactor Program Advanced Plant Safety & Licensing Nuclear Energy Institute Westinghouse Electric Corporation 1776 Eye Street, N.W.

Energy Systems Business Unit Suite 300 Box 355 Washington, DC 20006-3706 Pittsburgh, PA 15230 Ms. Lynn Connor Ms. Cindy L. Haag Doc-Search Associates Advanced Plant Safety & Licensing Post Office Box 34 Westinghouse Electric Corporation Cabin John, MD 20818 Energy Systems Business Unit Box 355 Mr. James E. Quinn, Projects Manager Pittsburgh, PA 15230 LMR and SBWR Programs GE Nuclear Energy Mr. M. D. Beaumont 175 Curtner Avenue, M/C 165 Nuclear and Advanced Technology Division San Jose, CA 95125 Westinghouse Electric Corporation One Montrose Metro Mr. Robert H. Buchholz 11921 Rockville Pike GE Nuclear Energy Suite 350 175 Curtner Avenue, MC-781 Rockville, MD 20852 San Jose, CA 95125 Mr. Sterling Franks Barton Z. Cowan, Esq.

U.S. Department of Energy Eckert Seamans Cherin & Mellott NE-50 600 Grant Street 42nd Floor 19901 Germantown Road Pittsburgh, PA 15219 Germantown, MD 20874 Mr. Ed Rodwell, Manager Mr. S. M. Modro PWR Design Certification Nuclear Systems Analysis Technologies Electric Power Research Institute Lockheed Idaho Technologies Company 3412 Hillview Avenue Post Office Box 1625 Palo Alto, CA 94303 l

Idaho Falls, ID 83415 Mr. Charles Thompson, Nuclear Engineer AP600 Certification NE-50 19901 Germantown Road Germantown, MD 20874

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WESTINGHOUSE - NRC MEETING l

ON AP600 NOTRUMP SBLOCA COMPUTER CODE FINAL VERIFICATION AND VALIDATION KARCH 13, 1997 l

MEETING ATTENDEES l

NAME ORGANIZATION EARL NOVENDSTERN WESTINGHOUSE LARRY H0CHREITER WESTINGHOUSE l

B0B OSTERRIEDER WESTINGHOUSE MIKE YOUNG WESTINGHOUSE ANDY GAGNON WESTINGHOUSE t

RALPH LANDRY NRC ALAN LEVIN NRC (PART TIME) l FRANK ODAR NRC l

BILL HUFFMAN NRC CHARLES THOMPSON DOE I

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l Attachment I l

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PRESENTATION HANDOUT MATERIAL l

FROM MARCH 13, 1997, MEETING ON AP600 NOTRUMP SBLOCA COMPUTER CODE FINAL VERIFICATION AND VALIDATION 1

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AGENDA March 13,1997 Thursday,8:00 am l

Westinghouse Rockville Office l

NOTRUMP NRC/W MEETING l

1. Introduction (Novendstern) l l

2. SPES Results (Gagnon)

3. OSU Results (Osterrieder)

4. ACRS Meeting (Young) l

a. Executive Summary

b. Proposed Agenda l

c. NRC Feedback on Approach

5. Documentation Closure (Osterrieder)

a. Report l

b. RAls/Open items /DSER 1

6, Wrap-up (NRC/W) l l

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E WESTINGHOUSE ELECTRIC CORPORATION E Analysis Of The SPES Facility With The Westinghouse NOTRUMP Code Prepared By:

A. F. Gagnon Advanced & VVER Plant Safety Analysis Westinghouse Electric Corporation I

Presented At:

Westinghouse Office Rockville, Maryland i

L March 13,1997 1

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E W E S TIN G H O U S E ELECTRIC CORPORATION E

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Overview Review Of Test Matrix NOTRUMP Noding Diagram t

Pressurizer Mixture Level Correction Review Of 2 Inch Cold Leg Break Results (Test S00303) t Discussion Of Revised 2 Inch Cold Leg Balance Line Break Results (Te

- Results Presented In Report Did Not Model Correct Break Location Discussion Of SPES Validation Report Summary Section (Section 7.4) i L

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B TABLE 7.2-1 g

I SPES 2 TEST MATRIX I

Test Description c

(AP600 Transient States Nonsafety.

AP600 Single Fadere

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Test No.

Test Type W) related systenes Sienelated Cosannent

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(S00401)

Small-Break 1-in cokileg break CVCS, NRHR, and One of two fourth-stage Maximize CMT heatup prior LOCA (Note 2), bottom of SFWS off. No operator valves on loop B to ADS actuation.

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loop B (Note 1) actions (OAs).

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Small-Break l-in. cold leg break, CVCS, NRHR Off; One of two fourth-stage This test deleted due to Al%00 LOCA bottom of loop B SFWS on (Note 3).

valves on loop B design changes.

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Small-Break 2-in. cold leg break, CVCS, NRHR, and One of two fourth-stage Reference cold leg break.

y (S00303)

LOCA bottom of loop B SFWS off. No OAs.

valves on loop B if (Note 4) i w

4 Small-Break 2-in. cold leg break,-

CVCS, NRHR, and One of two fourth-stage Nonsafety-related/ passive I or A bottom of loop B SFWS on (Note 3),

valves on loop B system interactions.

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Small-Dreak 2-in. DVI break CVCS, NRHR and Opc of two fodtth-stage Asymmetric CMT (S00605)

LOCA t

SFWS off. No OAs.

valves on loop B performance.

6 Small-Break DEG break of DVI CVCS, NRHR, and One of two stage I and Compleic loss of one-of-two (S00706)

LOCA SFWS off. No OAs.

stage 3 valves injection flow paths.

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Small-Break 2-in. break in cold CVCS, NRHR, and One of two fourth-stage Examine effect on CMT Jrain-I (S01007)

LOCA legM'MT-B balance line SFWS off va,ves on loop B down.

8 Small-Break DEG break of a cold CVCS, NRHR, and One of two stage I and No delivery from faulted i

(S00908)

LOCA legM'MT-B balance line SFWS off. No OAs.

stage 3 ADS valves CMT.

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Analysis of the OSU Facility With the Westinghouse i

NOTRUMP Code l

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l Bob Osterrieder l

l Westinghouse Electric l

March 13,1997 l

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Overview l

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0 Review of Test Matrix o

NOTRUMP Noding Diagram Review of 2 inch Cold Leg Break Results (Test SB18) o Discussion of OSU Validation Report Summary Section (Section 8.4) l o

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l 8.2.3 Selected Oregon State University Tests for Analysis l

A total of seven OSU tests (six small break LOCA tests and an inadvertent ADS actuation test) w selected for analysis with the NOTRUMP code. The selected tests cover the range of break locations and sizes that were tested in the OSU facility. All tests analyzed use only the passive emergency core cooling systems to mitigate the transient and to maintain core cooling. The tests include:

SB18: 2-in. cold leg break in the bottom of cold leg 3. This is a repeat of the reference test for j

the OSU test matrix and simulates a typical small-break LOCA case.

SB23: 0.5 in. cold leg break in the bottom of cold leg 3. This test is the smallest break performed for the facility and provides a break size comparison to the reference case.

SB13: 2-in. break in DVI line 1. This test provides a different break location for the same size l

l break as the reference case.

I SB12: double-ended DVIline break of DVIlirm 1. One half of the safety injection is lost to the containment. This break, along with test SB13, gives a break size sensitivity for the same break location.

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SB09: 2-in. cold leg balance line break is also a different break location for the same size break-as the reference test.

SB10: double-ended balance line break. This test, along'with test SB09, gives another break size j

sensitivity at a different break location.

SBl4: inadvertent ADS actuation. This test provides the system response to the no-break LOCA event.

The combinations of the selected OSU tests exercise the NOTRUMP code over a wide range of break sizes and locations, which allows examination of different performance aspects of the AP600 passive emergency core cooling systems so that the code is adequately validated.

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l m'ap600088l* 8 wpf ib-o20397 8,2. ] 7 Rev.I l

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l OSU 2 Inch Cold Leg Break (SB18) Results Summary l

o NOTRUMP Predicts Delayed ADS Actuation Relative to Test Data l

Test ADS Time = 390 seconds l

l SB18 Simulation = 548 seconds l

o Delays Related to Delay in Fluid in Top of CMTs Reaching Saturation Results in Delay in Start of CMT Draindown Phase l

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No Core Coverage Concerns Exhibited by NOTRUMP or Test

- NOTRUMP Predicts Lower System Mass During Most of Transients i

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Validation Report Summary Section for OSU i

o Timing Related issues i

l NOTRUMP Consistently Predicts Delayed ADS Actuation Relative to Test o

Flow Related Issues NOTRUMP Consistently Underpredicts the Mass Through ADS 1-3 Valves NOTRUMP Consistently Overpredicts Break Flow by the Same or Greater Amounts than the Underprediction of ADS 1-3 Flows o

NOTRUMP Consistently Under-predicts PRHR Heat Transfer

- Only impacts Small Break Sizes (Less than 2 Inches in Diameter) l I

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i NOTRUMP Consistently Predicts Conservative System inventory Relative to

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NOTRUMP VAllDATION MARCH 13,1997 l,

M.Y. YOUNG I

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l NOTRUMP

SUMMARY

REPORT t

PURPOSE:

To bring together the PIRT, descriptions of important NOThUMP models, and results from the FVR (Final Validation Report) in a form suitable for discussion with the ACRS subcommittee i

REPORT WILL EMPHASIZE AREAS OF PARTICULAR INTEREST TO ACRS:

- relationship of PIRT to key models f

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- assumptions and range of application j

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- deficiencies and assessment of impact i

REPORT WILL ALSO ADDRESS ISSUES RAISED IN NRC REVIEW OF FVR REPORT OUTLINE:

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KEY MODELS IDENTIFIED BY THE PIRT j

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KEY MODEL

SUMMARY

DESCRIPTIONS 111.

MODEL VALIDATION

SUMMARY

(SINGLE EFFECTS TESTS) / CONCLUSIONS IV.

INTEGRAL TEST VAllDATION

SUMMARY

/ CONCLUSIONS k

V.

AP600 APPENDlX K APPLICATION

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REPORT CONTENT t

REPORT WILL FOCUS ON (AND ALL RECENT CODE CHANGES WILL BE RELATED TO ) THE FOLLOWING KEY MODELS IDENTIFIED BY THE PIRT:

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- drift flux model (vertical and horizontal)

- mixture level tracking model

- hydraulic resistance model

- condensation heat transfer models for RCS

- heat transfer model for PRHR

- critical flow model

- thermal stratification model FOR EACH MODEL:

- describe in summary form (reference NOTRUMP sections for numerical or coding details)

-identify assumptions used in the model

- identify range of applicability, and demonstrate that calculations of AP600 and integral i

tests are within range most of the time i

- discuss separate effects validation results, what they indicate about potential compensating effects in integral tests

- discuss identified deficiencies, expected impact on results, and why code is still applicable I

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i REPORT CONTENT i

INTEGRAL EFFECTS TESTS:

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- evaluate code mis-predictions in terms of identified model deficiencies

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- conclude that system mass prediction is conservative, and compensating effects are known and understood AP600 APPENDIX K CALCULATION:

- discuss additional conservative assumptions l

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i EXAMPLE MODEL

SUMMARY

i MIXTURE LEVEL TRACKING MODEL:

DESCRIPTION:

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- includes bubble rise, fluid node stacking, mixture level overshoot, reflux flowlinks, contact coefficients code mods.

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- focus on calculation of vapor flow from two phase mixture to vapor bubble, not coding

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logic to make model work ASSUMPTIONS:

- stratified conditions are assumed to always exist j

- no entrainment of liquid from lower mixture to vapor phase RANGE OF APPLICABILITY:

- pool entrainment data will quantify importance of entrainment above the mixture level

- stratified break flow tests will quantify importance of entrainment to tees

- confirm that calculated conditions are within range most of the time I

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PROPOSED ACRS AGENDA FIRST DAY:

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INTRODUCTION L

brief overview of AP600 design and small break LOCA scenario 11.

NOTRUMP CODE OVERVIEW i

i development and licensing history overall code structure ill.

KEY MODELS IDENTIFIED BY THE PIRT t

l relationship of PlRT to phenomena, models used to simulate phenomena

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IV.

KEY MODEL DESCRIPTION / SEPARATE EFFECTS ASSESSMENT l

model summary t

f assumptions range of applicability f

validation l

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PROPOSED ACRS AGENDA SECOND DAY:

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INTEGRAL TEST ASSESSMENT present SPES, OSU comparisons VI.

CONCLUSIONS NOTRUMP is applicable for use in AP600 small break LOCA Vll.

AP600 APPENDIX K APPLICATION list Appendix K requirements which will be applied identify addnional conservative assumptions to be made identify conservative features identified by code assessment

t DOCUMENTATe0N CLOSURE Bob Osterrieder Westinghouse Electric

USE OF QUENCH MODEL o

Quench model developed for cases with core nodes that uncover then have some recovery o

Quench model originally used for all reported G2 runs o

Quench model originally used for all reported ACHILLES runs o

Code changes during project along with test cases indicated no need for use of quench model in final calculations therefore, quench model description not included in report o

in closing out documentation, repeated calculations with final code version, final options (quench model off, birthing off) o Repeat of base ACHILLES calculations with quench modc' off showed no difference in results Repeat of ACHILLES noding study Section 4.3.4 (4,12,24 & 48 nodes) l o

showed no difference in results except for 4 node case only (mixture level spikes - 4 node case uses quench model to eliminate spikes)

Section 4.3.4 concludes that we will use approximately 1 foot axial noding for NOTRUMP simulations of heated bundles or cores. Therefore,4 node case not l

used to justify bigger nodes and not important to support final model.

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Cuench model NOT USED for any reported OSU or SPES-2 runs o

Repeat of all G2 calculations indicated need for quench model for a few cases l

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TABLE 4.4 3 G2 LOOP CORE UNCOVERY TEST PARAS 1ETERS Initial Bundle Pressure Bundle Power Water Level Tests Analyzed I

Run Number (psia)

($1W)

(in.)

with NOTRU51P 1

715 779 0.603 114

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716 775 0.252 138

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l 717 796 0.905 102 718 799 1.258 90 l

719 394 0.267 138

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720 395 0.615 114

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721 394 0.914 102 722 395 1.264 84 723 395 0.614 114 724 96 0.252 126

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725 0.599 96

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726 96 0.857 84 i

l 727 97 1.247 78 728 50 0.596 84

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729 50 0.250 114

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730 50 0.894 66 731 50 1.244 54 732 15.1 0.254 102

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l 733 15.8 0.600 72

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i 734 16.1 0.900 60 735 16.7 1.249 54 l

736 15.3 0.253 102 I

mwass tw.4g wpf ib.121096 4.4-19 Rev.0 3

SUMMARY

OF G2 CASES WITH FINAL CODE VERSION AND OPTIONS (Ouench Model Of )

NSD = No significant difference Case Base High Leakage Low Leakage 715 NSD NSD NSD 716 NSD NSD NSD 719 NSD NSD NSD 720 NSD NSD NSD 724 NSD NSD NSD 725 NSD NSD NSD 728 NSD NSD mixture level spike

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729 mixture level NSD NSD spikes 732 mixture level mixture level mixture level spike spikes spike 733 run aborted run aborted some early

- 200 sec

~ 220 sec differences, level spikes I

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RESULTS OF USE CF QUENCH MODEL FOR G2 CALCULATIONS o

Most cases don't need quench mod;l o

Quench model eliminates mixture levol spiking o

Mixture levels trends similar with or without spikes l

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Demonstration of code prediction of level swell based on GE, ACHILLES, and G2 l

Report already indicates that G2 calculations have much uncertainty o

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Not planning to use quench model for plant design basis. calculations since no i

uncove.7 n analyzed cases i

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Plan to 1)

Indbate in G2 section of report that quench model exists and which cases use it I

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Include new plots for cases with quench modelincluded in G2 section of report 3)

Include reference to T/H Uncertainty report for description of quench model l

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i SDSER Confirmatory Description of item Reference Where Answered item #

DSER-CN 21.6.2.4 1 The application of SIMARC drift-flux is The NOTRUMP FVR (WCAP-acceptable pending confirmation of the 14807, Revision 1) has been model through benchmark and submitted.

assessment of code to be provided in i

NOTRUMP Final Validation Report (FVR).

DSER-CN 21.6.2.4-2 The modifications made to the The NOTRUMP FVR (WCAP-NOTRUMP drift-flux correlations are 14807, Revision 1) has been acceptable pending confirmation of the submitted.

model through benchmark and assessment of code to be provided in NOTRUMP FVR.

DSER-CN 21.6.2.4-3 Westinghouse needs to verify that the i

NOTRUMP code does not use the Bjornard and Griffith modification.

DSER-CN 21.6.2.4-4 Westinghouse needs to verify that heat link methodology for transition boiling is not used in AP600 NOTRUMP calculations.

DSER-CN 21.6.2.5-1 The acceptability of the PRHR model used in NOTRUMP is contingent on a finding that the PRHR data are applicable.

DSER-CN 21.6.2.7 1 Comparisons of the NOTRUM? code The NOTRUMP FVR (WCAP-simulations to the OSU and SPES-2 test 14807, Revision 1) has been data in the NOTRUMP FVR should submitted.

confirm the applicability or insensitivity of the NOTRUMP flow regime models to the key system response parameters.

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SDSER Open item #

Description of item Reference Where Answered DSER-OI 21.6.2.2-1 Westinghouse needs to identify which This table identifies where RAI information from the NOTRUMP-related information is captured and RAI responses will be incorporated into closes the 01. Note that the NOTRUMP-related documentation.

NOTRUMP FVR is intended to be the only NOTRUMP related documentation summarizing the NOTRUMP code for use on AP600 plant calculations.

DSER-OI 21.6.2.2-2 Westinghouse needs to submit the The NOTRUMP FVR (WCAP-NOTRUMP FVR.

14807, Revision 1) has been submitted.

DSER-Ol 21.6.2.4-1 Westinghouse needs to explain provisions to ensure that volumetric-based momentum equations will be used for all AP600 calculaticos.

DSER-Of 21.6.2.4-2 Westinghouse needs to submit the The NOTRUMP FVR (WCAP-assessment cases demonstrating 14807, Revision 1) has been acceptability of casting equations in net submitted. Section 3.5 contains volumetric form.

the assessment cases.

DSER-Of 21.6.2.4-3 Westinghouse needs to submit the After the preliminary calculations, assessment cases for the Horizontal this model was no longer used.

Stratified Flow Model.

The preliminary calculations were redone without this model, and therefore the model description is not included in WCAP-14807. As e result, the assesments are not needed and not performed.

DSER-OI 21.6.2.4-4 Westinghouse needs to explain provisions to ensure that options to override the default flow partitioning will be used for all AP600 calculations.

DSER OI 21.6.2.4-5 Final acceptance of Mixture Overshoot The NOTRUMP FVR (WCAP-l Logic must await completion of 14807, Revision 1) has been benchmark and assessment calculations submitted.

to be incipoed in NOTRUMP FVR DSER-Ol 21.6.2.4-6 Determination of additional (to G-2 tests)

Section 4 of WCAP 14807, separate effects level swell tests Revision 1 contains GE and necessary for code qualification.

ACHILLES separate effect level swell test simulations in addition to G 2.

DSER OI 21.6.2.4-7 Acceptance of modified pump model Benchmark submitted in Section must await submittal of benchmark 3.7 of WCAP-14807, Revision 1 calculations.

DSER-OI 21.6.2.4-8 Acceptance of implicit treatment of Benchmark submitted in Section gravitational head await staff review of 3.4 of WCAP-14807, Revision 1 the benchmark calculations.

DSER Ol 21.6.2.4-9 Acceptance of the horizontal flow Benchmark submitted in Section levelizing model must await submittal 3.3 of WCAP 14807, Revision 1 and staff review of benchmark calculations.

DSER-Ol 21.6.2.4-10 The staff cannot determine the adequacy After the preliminary calculations, of the birthing logic until benchmark is this model was no longer used.

submitted and reviewed.

The preliminary calculations were redone without this model for inclusion in WCAP-14807, Revision 1. As a result, no benchmark was pedormed and the staff does not need to review the birthing logic.

DSER Ol 21.6.2.4-11 Acceptance of the Zuber critical heat flux Tne NOTRUMP FVR (WCAP-correlation for AP600 SBLOCA analysis 14807, Revision 1) has been will be determined after review of the submitted. SiA% 2. 8 f NOTRUMP FVR.

T3 K M 4vro -TH Mr w/t J

DSER-Ol 21.6.2.4-12 Acceptance of the smoothing logic The NOTRUMP FVR (WCAP-between choked and unchoked flow must 14807, Revision 1) has been await submittal and review of the Final submitted.

NOTRUMP Validation Report.

DSER-OI 21.6.2.4-13 Acceptance of the logic schemes for The NOTRUMP FVR (WCAP-application of fluid node stacking, mixture 14807, Revision 1) has been level overshoot, and bubble rise changes submitted.

must await the submittal of the assessment cases in the NOTRUMP FVR.

DSER-Ol 21.6.2.5-1 The NOTRUMP code tended to The NOTRUMP FVR includes the overpredict the ADS flow rates in the OSU and SPES-2 simulations preliminary OSU and SPES-2 which were redorie after the comparisons. The models affecting the preliminary calculations. Included fluid entering the ADS piping, particularly in the report are comparisons for the hot legs and pressurizer, need to (test data to simulation) of ADS be reviewed in the NOTRUMP FVR.

flows.

DSER-OI 21.6.2.5-2 CMT thermal stratification was not Section 6 of the NOTRUMP FVR captured in the CMT tests.

contains the CMT test simulations Westinghouse will further investigate which were redone after the inability to properly characterize CMT preliminary calculations.

thermal stratification and these l

assessments will be provided in the l

NOTRUMP FVR.

1 DSER-Of 21.6.2.5-3 The staff must receive and evaluate the Sections 5 and 6 of the CMT and ADS test sirnulations that were NOTRUMP FVR contain these identified in Table 21.7 of the SDSER.

test simulations.

I W

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~'

D3ER O! 21.6.2.61 The staff must receive and evaluate the benchmark calculations that were Section 3 of the NOTRUMP FVR identified in Table 21.8 of the SDSER.

contains these benchmarks with the exception of the Birthing Logic and Horizontal Stratified Flow ones which were not performed because the coding was not used in the NOTRUMP FVR calculations and will not be used in AP600 plant calculations.

DSER-Of 21.6.2.6-2 The staff must receive, review, and Section 4 of the NOTRUMP FVR evaluate the adequacy of the separate-effects testing relative to level swell and contains the level swell related test simulations.

void fraction distribution.

DSER-Ol 21.6.2.6-3 The staff must receive and evaluate the integral test simulations that were Sections 7 and 8 of the NOTRUMP FVR contain the identified in Table 21.10 of the SDSER.

integral test simulations.

DSER-OI 21.6.2.7 1 Westinghouse needs to address PRHR primary side heat transfer comparisons The comparisons for SPES-2 are between NOTRUMP and OSU/SPES-2 contained in Section 7 of the data in the NOTRUMP FVR.

NOTRUMP FVR. OSU comparisons were not included because comparable test data was not available.

'DSER-Ol 21.6.2.7-2 Effects of non condensible gases on PRHR heat transfer should be addressed in NOTRUMP FVR.

i DSER Ol 21.6.2.7-3 Clarify the use of the COSI condensation modelin the AP600 code.

l l

I

I l.

RAI#

Description of item Reference Where Answered RAI 440.325 Questions on NOTRUMP CAD (WCAP.

Westinghouse Letter 14206) related to PIRT, NOTRUMP NTD-NRC-95-4594; modeling of noncondensible gases, and WCAP-14807, Revision 1 l

NOTRUMP 1-D model.

Section 1.3 contains final i

SBLOCA PIRT.

RAI 440.326 Should include an AP600 plant Westinghouse Letter nodalizaticn and reference to SAR NTD-NRC-95-4587; calculations.

WCAP-14807, Revision 1 l

Section 1.2 contains AP600 plant noding diagram.

RAI 440.327 Provide a matrix of tests that will be used Westinghouse Letter for assessing each of the PIRT items.

NTD NRC 95-4610; Also, identify the models that are to be WCAP-14807, Revision 1

)

validated for each test.

Section 1.4 contains table of tests and parameters selected for validation of NOTRUMP for highly ranked PIRT items.

RAI 440.328 Explain what analyses were performed to Westinghouse Letter determine the limiting failure.

NTD-NRC-95-4587 l

RAI 440.329 Describe the low flow correlations Westinghouse Letter applicable to the prediction of the single NTD-NRC-95-4610 and two-phase friction factors in l

NOTRUMP for AP600 and identify the l

test data that will be used for the l

assessment.

l RAI 440.330 Describe the enhancements made to the Westinghouse Letter l

NOTRUMP code for AP600.

NTD-NRC-95-4587; WCAP 14807, Revision 1, Section 2 contains the NOTRUMP code changes for AP600 calculations.

RAI 440.331 Provide the specific inputs for he code Westinghouse Letter extemals used to perform the analyses in NTD-NRC-96-4630 the SSAR calculations done in January 1994.

RAI 440.332 Provide a document describing the Westinghouse Letter methods and models comprising the long NSD-NRC-96-4780 l

term cooling code and describe how the code is initialized from the NOTRUMP code.

RAI 440.333 Justify the use of a fixed containment Westinghouse Letter pressure boundary condition since the NSD-NRC-96-4780 response of the safety systems depend on containment pressure.

J

RAI 440.334 Provida a test matrix showing the Westinghouse Letter separate effects and integral tests to be NTD NRC-95-4610;

(

used in the validation of NOTRUMP for WCAP 14807, Revision 1, AP600.

Section 1.4 contains table of tests and parameters selected for validation of NOTRUMP.

RAI 440.335 Justification for using constant friction factors, particularly at low flow, flow l

pressure conditions are needed.

I l

RAI 440.336 Describe if momentum flux is included in AP600 analyses and jusory its omission if it is not used.

RAI 440.337 Demonstrate that the Macbeth correlation is adequate for the low flow and pressure l

conditions expected for AP600.

I l

RAI 440.338 Demonstrate that the NOTRUMP pump j

model can predict the AP600 pump coastdown. Describe and justify the use of the two-phase pump degradation curves for AP600 analyses.

RAI 440.339 Provide time step and nodalization 1

j studies to justify the AP600 nodalization.

RAI 440.340 Discuss the potential for boric acid build-Westinghouse Letter up and precipitation during long NSD-NRC-96-4780 transients for AP600.

l RAI 440.341 Describe in detail the IRWST model Westinghouse Letter i

including how the sparger and plumes NTD-NRC-95-4587 are handled as well as their influence on IRWST injection and PRHR heat removal.

l RAI 440.342 Provide documentation for a) NOTRUMP coding changes along with model benchmarks, b) a description of the containment modeling approach with calculations justifying model, c) a l

description of the "Long Term Cooling Code", d) a section presenting calculative methods including sensitivity studies and the full break spectrum l

analysis, and e) a test matrix listing the pertinent separate and integral tests used to benchmark the AP600 small i

break LOCA code package.

4 RAI 440.432 identify where choking occurs in the ADS Westinghouse Letter tests and discuss why the asymetric NTD-NRC-95-4610 effects can be ignored in modeling the three ADS valves as a single flow path.

4

l RAI 440.433 Explain the effect of not modeling air in Westinghouse Letter the ADS lines on the ADS system NTD NRC 95-4610 pressure, flow, and quality responses.

RAI 440.434 Demonstrate the ability of the NOTRUMP code to accomodate single phase steam l

critical flow since the ADS system is expected to transition to high quality steam flow discharge.

RAI 440.435 Questions related to ADS modeling Westinghouse Letter including explain how NOTRUMP treats NTD-NRC-95-4594 the void distribution and release of steam from the two-phase regions in the ADS l

lines.

i RAI 440.436 Explain how NOTRUMP uses equation Westinghouse Letter 4-1 of RCS-GSR-003 in computations of NTD-NRC-95-4598 fluid quality.

RAI 440.437 Questions on ADS test simulation Westinghouse Letter depressurization rates and length of test NTD-NRC-95-4594 simulations, l

RAI 440.438 Explain the inconsistency in the Westinghouse Letter l

discussion of the effect of tank pressure NTD-NRC-95-4587 on qua!ity in the ADS Preliminary Validation Report.

RAI 440.439 Has the NOTRUMP code been assessed Westinghouse Letter against single-phase and two-phase NTD-NRC-95-4610 pressure drop test data in piping systems with expansions and contractions present?

RAI 440.440 Provide the results of a noding study Westinghouse Letter l

used to justify the CMT noding in the NTD-NRC-96-4622 CMT Preliminary Validation Report.

Also, provide the plots of the fluid driving heads calculated by NOTRUMP for each side of the loop.

RAI 440.441 Were wall temperatures measured in the facility in the CMT and piping? If so, provide comparisons with the NOTRUMP code and discuss the results.

l RAI 440.442 Were wall heat structures modeled in the l

piping and reservoir? If not, justify the omission; it so describe the model.

RAI 440.443 Justify the reservoir nodalization and explain the effects of thermal stratification and mixing, or lack thereof, in the SM/ reservoir on the NOTRUMP results.

=

l 1

l RAI 440.444 Was a time step study performed for the l

CMT tests? Discuss and show tha' the l

time steps used do not contribute io the l

error in the NOTRUMP predictions. Are the time steps consistent with those used in the plant model?

RAI 440.445 The early CMT flow rates appear to be Westinghouse Letter overpredicted even though the time NTD-NRC-96-4626 averaged flows show good comparisons.

l Discuss the NOTRUMP behavior given that the early overprediction of flow may affec' the RCS loop temperatures and system behavior later in the event.

RAI 440.446 Explain why the CMT inlet flow l

uncertainty is higher than the outlet flow uncertainty measurement fx the test.

Explain this uncertainty in light of the l

NOTRUMP inlet flow rate predictions.

RAI 440.463 Justify use of single node for SG Westinghouse Letter secondary sido.

NTD NRC-95-4587 RAI 440.464 Perform two-phase level swell WCAP 14807, Revision 1 simulations to justify core noding.

Section 4 for level swell, Sections l

4.2.5 and 4.3.4 for noding j.

RAI 440.465 Justify omission of wall heat transfer Westinghouse Letter l

from loop piping and secondary NTD-NRC-95-4594 components.

RAI 440.466 For SIMARC drift flux model... Please WCAP-14807, Revision 1

(

describe how the void fraction is Section 2.2 computed for countercurrent flow conditions.

RAI 440.467 Two drift flux models were added to Westinghouse Letter NOTRUMP. Which modelis to be used NTD NRC-95-4587; for AP600 cales? Explain models.

WCAP 14807, Revision 1 Section 2.3 RAI 440.468 Provide benchmark cafes for level swell WCAP-14807 Revision 1 and counter current flow data to evaluate Section 4 for level swell, flooding.

Sections 3.2 & 3.3 for flooding RAI 440.469 Provide volumetric flow based WCAP-14807, Revision 1 l

momentum equations and code Section 2.4 for equations, l

benchmarks for this model change.

Section 3.5 for benchrpark RAI 440.470 Questions on Horizontal Stratified Flow After the preliminary calculations, 1

Model in preliminary NOTRUPAP report this model was no longer used.

LTCT-GSR 001 The preliminary calculations were redone without this model, and I

therefore the model description is not included in WCAP-14807. As

{

a result, the RAI no longer applies.

RAI 440.471 Discuss the use of partitioning models for Westinghouse Letter AP600 calculations and show that there NTD NRC-95-4598 use would not adversely affect the level swell results.

RAI 440.472 Please explain the liquid reflux flow links Westinghouse Letter and how their use affects level swell, NTD-NRC-95-4594 bubble rise, steam production, and fuel cooling.

RAI 440.473 Please explain how the mixture level Westinghouse Letter l

overshoot logic does not introduce errors NTD-NRC 95-4587; into the NOTRUMP solution that could WCAP-14807, Revision 1 l

change the results or conclusions of an Section 2.8 AP600 analysis.

RAI 440.474 Provide the derivations and the WCAP-14807, Revision 1 expressions for the equations comprising Section 2.9 for equations, l

the implicit bubble rise model. Provide Section 3.6 for benchmark, level swell calculations verifying this Section 4 for level swell model.

RAI 440.475 Provide a mathematical description of WCAP-14807, Revision 1 modified pump model and comparison Section 2.10 for equations, t

of the old to new model.

Section 3.7 for comparison RAI 440.476 Describe mathematically the implicit WCAP 14807, Revision 1 treatment of gravitational head and Section 2.11 for equations, l

provide verification analysis.

Section 3.4 for verification benchmark l

RAI 440.477 Provide new levolizing drift velocity WCAP-14807, Revision 1 i

correlation and provide a benchmark for Section 2.12 for correlation, j

model.

Section 3.3 for benchmark RAI 440.478 Provide a sample calculation showing After the preliminary calculations, how the birthing region works.

this model was no longer used.

The preliminary calculations were redone without this model, and therefore the model description is not included in WCAP-14807. As a result, the RAI no longer applies.

RAI 440.479 Provide a comparison of the NOTRUMP Westinghouse Letter i

Shah condensation model prediction to NTD NRC-96-4626 l

condensation test data demonstrating applicability of the model to the range of conditions expected in AP600.

RAI 440.480 Provide a comparison of the results of Westinghouse Letter the as implemented Zuber critical heat NTD-NRC-96-4626 flux correlation to test data over the range of conditions expected for AP600 small break LOCAs.

l

e. :* e RAI 440.481 Provide comparisons of the new Westinghouse letter NOTRUMP two-phase friction multiplier NTD-NRC-95-4598; l

to separate effects and/or integral test WCAP 14807, Revision 1, data below 250 psia to justify the new Section 2.16 l

models extrapolation formulation.

l RAI 440.482 Provide benchmark of the new critical Westinghouse Letter l

flow model versut critical flow tests to NTD-NRC-96-4630; i

verify the model. Describe how the WCAP-14807 Revision 1, model treats the transition from choked Section 2.13 describes the to unchoked conditions.

transition from choked to unchoked conditions.

l RAI 440.483 Provide results of a sample fill and drain WCAP 14807, Revision 1 calculation to demonstrate the Fluid Section 2.18 for description, Node Stacking Logic and provide a Section 3.8 for demonstration mathematical description of tha logic.

RAI 440.484 Show the effect of the changes to the Westinghouse Letter transition boiling correlation on peak clad NTD-NRC-95-4594 temperature.

RAI 440.485 Describe the coding and model changes Westinghouse Letter included in the preliminary ADS test NTD-NRC-96-4630; simulations and CMT test simulations These simulations were redone and included in WCAP-14807, Revision 1 RAI 440.486 Explain why in the preliminary OSU Westinghouse Letter simulations the upper head drains NTD-NRC 95-4598; prematurely in the tests.

These simulations were redone and included in WCAP-14807 Revision 'l RAI 440.487 For the analyses in the OSU Preliminary Validation Report (PVR), provide comparisons of the NOTRUMP liquid levels in the core and upper plenum i

versus test data.

l RAI 440.488 Discuss the NOTRUMP overprediction of the integrated break flow for the OSU PVR calculation.

RAI 440.489 Explain why the NOTRUMP code l

underpredicts the PRHR heat transfer in i

the OSU PVR and justify how this model results in conservative AP600 SBLOCA ECCS performance predictions.

i RAI 440.490 Explain why the NOTRUMP code ove@redicts the downcomer liquid level during this OSU PVR calculation and justify the model result for @600 plant J

calculations.

- -. ~

e e,

-i RAI 440.491 Provide the core inlet and core bypass mass flow rate predictions for the NOTRUMP code.

RAI 440.492 Provide the core inlet and bypass mass flow rate predictions for the blind two l

Inch cold leg balance line break in the OSU PVR. Also provide the liquid level plots for the upper plenum and core a

region and the void distribution in the l

core region.

RAI 440.493 Discuss the NOTRUMP fast depressurization rate for OSU PVR calculations including the break flow discharge coefficient and the steam generator heat transfer.

RAI 440.494 Discuss the impact of the delayed CMT 2 drainage on the core / upper plenum level response for the OSU PVR calculation.

RAI 440.495 Provide the upper plenum and core liquid level plots for this test along with the void distribution in the core.

RAI 440.496 For this OSU PVR calculation explain why the code overpredicts the liquid inventory in the downcomer and justify t

that this will not lead to non-conservative predictions of the liquid level in the vessel for AP600 plant calculations.

RAI 440.497 Explain the statement that the NOTRUMP code allows a "short spurt of flow at the break"in reference to Figure 5.3-22 of the OSU PVR.

RAI 440.498 For this OSU PVR case, explain the reasons for the highly oscillatory behavior in the PRHR inlet flow calculated by NOTRUMP and why the code predicts a much higher PRHR flow i

rate.

RAI 440.499 Can the NOTRUMP code model nitrogen entering the RCS? If not, juctify the omission of nitrogen effects on AP600 response following small break LOCAs.

L RAI 440.500 l

l RAI 440.501 I

RAI 440.502 l

RAI 440.503 RAI 440.504

'n o

l l

j RAI 440.505 RAI 440.506 RAI 440.507 RAl 440.508 RAI 440.509 l

l RAI 440.510 RAI 440.511 RAI 440.512 l

RAI 440.513 RAI 440.514 RAI 440.515 RAI 440.516 RAI 440.517 RAI 440.518 l

RAI 440.519 RAI 440.520 RAI 440.541 i

RAI 440.542 l

RAI 440.543 l

l RAI 440.544 RAI 440.545 l

RAI 440.546 RAI 440.547 RAI 440.548 RAI 440.549 I

RAI 440.550 RAI 440.551 l

RAI 440.552 RAI 440.553 4

-,